Центральная Научная Библиотека УрО РАН

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   S 53

    Shein, I. R.
    Structural, elastic and electronic properties of superconducting anti-perovskites MgCNi3, ZnCNi3 and CdCNi3 from first principles [Text] / I. R. Shein, V. V. Bannikov, A. L. Ivanovskii // Physica C: Superconductivity and Its Applications (Amsterdam, Netherlands). - 2008. - Vol. 468, № 1. - P1-6. - Bibliogr. : p. 6 (29 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
СВЕРХПРОВОДЯЩИЕ АНТИПЕРОВСКИТЫ -- УПРУГОСТЬ
Аннотация: First principle total energy calculations using the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential were performed to investigate the systematic trends for structural, elastic and electronic properties of the family of superconducting anti-perovskites MCNi3 depending from the type of M cations (M are Mg, Zn and Cd). In result the optimized lattice parameters, independent elastic constants (C11, C12 and C44), bulk modulus B, compressibility b, shear modulus G and tetragonal shear modulus G0 are evaluated. Further, for the first time the numerical estimates of a set of elastic parameters (bulk and shear modulus, Young’s modulus Y, Poisson’s ratio (m), Lame´’s coefficients (l, k)) of the polycrystalline superconducting MCNi3 ceramics (in framework of the Voigt–Reuss–Hill approximation) were performed. Besides, the band structures, densities of states (DOS), total and site-projected l-decomposed DOS at the Fermi level, the shapes of the Fermi surfaces, the Sommerfeld’s coefficients and the molar Pauli paramagnetic susceptibility for these anti-perovskites were obtained and analyzed in comparison with the available theoretical and experimental data

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   S 53

    Shein, I. R.
    The influence of oxygen vacancies on the electronic and magnetic properties of perovskite-like SrFeO3-x [Text] / I. R. Shein, V. L. Kozhevnikov, A. L. Ivanovskii // Journal of Physics and Chemistry of Solids. - 2006. - Vol. 67, № 7. - P1436-1439. - Библиогр. : с. 1439 ( 28 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
ОКСИДЫ -- AB INITIO РАСЧЕТЫ -- ЭЛЕКТРОННАЯ СТРУКТУРА -- ДЕФЕКТЫ -- МАГНИТНЫЕ СВОЙСТВА
Аннотация: The electronic, magnetic properties and lattice relaxations of oxygen-deficient cubic strontium ferrite, SrFeO2.875, in ferromagnetic configuration are studied by means of the density functional theory using LCAO basis (SIESTA code) calculations. It is shown that Fe and Sr atoms are displaced from oxygen vacancies while oxygen anions are attracted to the vacancies. The DOS distributions, magnetic moments and atomic effective charges are analyzed in comparison with vacancy free SrFeO3; these parameters are found to change weakly with appearance of oxygen vacancies, in contrast to conventional ionic picture. Some strengthening of Fe–O covalent bonds in the vicinity of the oxygen vacancy is found. The formation energy of oxygen vacancies and divacancies are evaluated

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   S 53

    Shein, I. R.
    First-principle study of B1-like thorium carbide, nitride and oxide [Текст] / I. R. Shein, K. I. Shein, A. L. Ivanovskii // Journal of Nuclear Materials. - 2006. - Vol. 353, № 1-2. - С. 19-26. - Bibliogr. : p. 26 (28 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
КАРБИД ТОРИЯ -- НИТРИД ТОРИЯ -- ОКСИД ТОРИЯ -- ПЕРВОПРИНЦИПНЫЕ РАСЧЕТЫ
Аннотация: The electronic properties of cubic (B1-type) thorium carbide (ThC), nitride (ThN) and meta-stable monoxide (ThO) were calculated systematically using the full-potential linearized augmented plane wave method with the generalized gradient approximation for the exchange and correlation potential (LAPW–GGA). The structural parameters, bulk modulii, electronic bands, densities of states (DOS), charge distributions were obtained and compared with available experimental data and other calculations. The theoretical spectra of non-metal K-edge X-ray emission (XES) and absorption (XAS) of these materials are presented and discussed

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   S 53

    Shein, I. R.
    Influence of lattice vacancies on the structural, electronic, and cohesive properties of niobium and molybdenum borides from first-principles calculations [Text] / I. R. Shein, A. L. Ivanovskii // Physical Review B: Condensed Matter and Materials Physics. - 2006. - Vol. 73, № 14. - P144108/1-144108/9. - Библиогр. : с. 144108/8 (55 назв.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
БОРИД МОЛИБДЕНА -- БОРИД НИОБИЯ -- ПЕРВОПРИНЦИПНЫЕ РАСЧЕТЫ
Аннотация: The influence of lattice vacancies on the structural, cohesive, and electronic properties of Nb and Mo borides were examined by means of the full-potential linearized augmented plane wave method and the generalized gradient approximation. The structural parameters, densities of states (DOS), charge distribution, heats of formations, and vacancy formation energies for metal-deficient hexagonal Nb1−xB2, Mo1−xB2 as well as for boron-deficient rhombohedral Mo2B5−y were obtained and compared with those for complete hexagonal NbB2, MoB2 and rhombohedral Mo2B5. We show that the presence of metal vacancies in hexagonal phases leads to (i) the decreasing of in-plane parameter a but increasing the interplane cell parameter c; (ii) well pronounced changes of near-Fermi DOS and the appearance of the novel vacancy states; and (iii) a substantial decrease in the stability of borides. On the contrary, in the case of Mo2B5 the appearance of the boron vacancies leads to enhancing of stability of a rhombohedral phase

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   S 53

    Shein, I. R.
    Electronic structure, ferm surface and elastic properties of the new 7.5K superconductor Nb2InC from first principles / I.R. Shein, A.I. Ivanovskii // Письма в журнал экспериментальной и теоретической физики. - 2010. - Т. 91, № 7-8. - С. 446-450 : рис., табл., граф. - Библиогр.: с. 449-450 (37 назв.) . - ISSN 0370-274X

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
СВЕРХПРОВОДНИК Nb2InC -- ЭЛЕКТРОННАЯ СТРУКТУРА -- ФЕРМИ СВОЙСТВА -- УПРУГИЕ СВОЙСТВА
Аннотация: First-principles calculations were performed to investigate electronic and elastic properties of the newly discovered 7.5 К superconductor: layered Nb2InC. As a result, electronic bands, total and site-projected l - decomposed DOS at the Fermi level, shape of the Fermi surface for Nb2InC were obtained for the first time. Besides, independent elastic constants, bulk modulus, compressibility, shear modulus, Young's modulus, Poisson's ratio together with the elastic anisotropy parameters and indicator of brittle/ductile behavior of Nb2InC were evaluated and analyzed in comparison with the available data

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   S 53

    Shein, I. R.
    Electronic properties of the novel 18-K superconducting Y2C3 ascompared with 4-K YC2 from first principles calculations / I. R. Shein, A. L. Ivanovskii // Solid State Communications. - 2004. - Vol. 131. - P. 223-227 : il. - Bibliogr. : p. 226-227 (18 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
СВЕРХПРОВОДНИКИ -- РАСЧЕТЫ ПЕРВОПРИНЦИПНЫЕ -- КАРБИД ИТТРИЯ
Аннотация: The electronic band structure and ground state properties of the recently discovered 18-K superconducting Y2C3 material Akimitsu et al., 2004) have been examined by the full-potential linear muffin-tin method–generalized gradient approximation method and compared with those of the 4-K superconductor YC2. The calculations show that the growth of TC for the yttrium sesquicarbide as compared with 4-K YC2 may be due to the electronic factor: the near-Fermi DOS for Y2C3 was found to be about 36.7% higher that for YC2. The Fermi level of the "ideal" Y2C3 is located near the local DOS minimum, and thesuperconductivity of Y2C3-based materials will be very sensitive to synthesis conditions (for example, pressure and annealing effects) and the presence of various impurities and lattice vacancies. Probably these factors may be used to vary the superconductivity of the Y2C3 phase over a wide range

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   S 53

    Shein, I. R.
    First-principles calculations of elastic and electronic properties of tetragonal Th2NiC2 as a parent phase for new superconductors / I. R. Shein, A. L. Ivanovskii // Journal of Alloys and Compounds. - 2013. - Vol. 551. - P338-342 : il. - Bibliogr. : p. 341-342 (36 ref.)

ББК 54
Рубрики: ХИМИЧЕСКИЕ НАУКИ
Кл.слова (ненормированные):
Th2NiC2 -- ELASTIC PROPERTIES -- AB INITIO CALCULATIONS -- INTER-ATOMIC BONDING -- ELECTRONIC PROPERTIES
Аннотация: This work reports on the elastic, electronic properties and inter-atomic bonding of the newly discovered superconductor Th2NiC2 as obtained within ab initio calculations. We found that Th2NiC2 is mechanically stable and it will behave as a ductile material exhibiting enhanced elastic anisotropy in shear and a rather low hardness. The inter-atomic bonding in Th2NiC2 is described as an anisotropic mixture of covalent and ionic contributions, where inside [Th2C2] blocks covalent Th–C bonds emerge, and these blocks are bonded with the Ni atomic sheets through directional Ni–C bonds. Additionally, some inter-atomic ionic Th–C interactions occur owing to charge transfer Th → C. Our data reveal that for Th2NiC2 the Fermi level is located in a deep DOS minimum and the experimentally observed increase in TC in the sequence Th2NiC2 → Th1.8Sc0.2NiC2 may be explained by the growth of N(EF). We also speculate that an increase in N(EF) (and, probably, in TC) for Th2NiC2-based materials may be also achieved by an alternative way: by electron doping – for example, by partial substitution of V for Th or Cu for Ni, as well as by partial substitution of N for C with the formation of Th–Ni carbonitrides like Th2NiC2−xNx

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